1) Remote work does not necessarily mean WFH. It means work where is most effective for you instead of going to some office. These days there are many different kinds of solutions for having office space if you want/need it. It also becomes more of a commodity that you can simply use when needed (e.g. a final push before release, a workshop preparing for a big new project, etc.).
2) Companies who recognise this and get rid of their local offices may experience a cost advantage because having offices costs more than just the building. There are a lot of utility costs involved, you need people who manage the facilities, etc., etc.
3) If we're really serious about the environment, avoiding people having to commute to work should be a serious goal. Companies tend to talk about reducing how much they fly around but what is the Co2 footprint of flying in total compared to commuting?